Telephone transmission system



June 4 .1924. 1,498,945

\ y W. H. BENDERNAGEL TELEPHONE TRANSMISS I ON SYSTEM Filed Dec. 22 1919 f0 opera/0h? fe/epbone Patented June 24, 1924.

UNITED STATES PATENT OFFICE.

WILLIAM H. BENDERN41.GEL, O QUEENS, NEW YORK, ASSIGNOR T0 WESTERN ELEC- TRIC CQMFANY, INGQYR-PORATED, OF NE'W' YORK, N. '55., A. CORPORATION 015 NEW YORK.

TELEPHONE TRANSMISSION SYSTEM.

Application filed December 22, 1919.

To 11, 1 whom it may concern:

Be it known that T, TVILIJAM H. Brianne- Nnonii. a citizen of the United States. residing at Queens, in the county of Queens, State of lew York, have invented certain new and useful Improvements in Telephone Transmission Systems, of which the following is a full, clear, concise, and exact description.

This invention relates to telephone trans mission systems and more particularly to such systems in which repeaters are employed. The object of the invention is to improve transmission over trunks connecting operators positions by including in such trunks amplifying apparatus without disturbing the normal function of the usual signaling arrangements, which provide for supervision of the call by other operators.

One of the features of the invention is to employ an amplifying repeater in an incoming trunk circuit of a telephone system. Another feature is to render the repeater operative only when connection is established and when ringing current is not being applied. Another feature is to provide signals for the operators and to use the trunk signal relay to indicate that the trunk has been taken for use and to render the amplifier operative. Another feature is to pro vide an incoming trunk circuit with apparatus tor ringing around the repeater. Another teature is to supply talking current from the link circuit to one subscriber and from the trunk circuit to another subscriber. Other features and advantages of the invention will be obvious as the description proceeds.

The invention will be understood from the description in connection with the drawings in which two embodiments of the invention are illustrated.

In the drawings, Fig. 1 shows a trunk circuit in which is employed two one-way am.- pliiiers in an incoming trunk circuit which is provided with apparatus for preventing ringing current from going through the repeaters and with apparatus for controlling the supervisory signals.

Fig: 2 shows two one-way amplifiers in a trunk circuit provided with apparatus for ringing around the repeater and with apparatus for controlling the signals.

In Fig. 1 reference character A represents an operators cord or link circuit provided Serial No. 3&6,584.

with the usual equipment. X and Y repre sent operators positions at the respective position Y, the operator at X inserts her plug P into the ack J of the trunk circuit, which the operator at Y has assigned for that purpose. thereby closing circuit from ground, battery, lamp L, sleeve contacts of plug P and jack J, to ground, thereby lighting the lamp L. Plugging in P simultaneously closes a circuit from battery of the cord circuit through the tip contacts of plug P and jack J, upper half of primary oi transformer T, high and low resistance windings of relay t, which are in series, lower half of primary winding of transformer T, through ring contacts of plug and jack, relay 5, to battery. The relay 4 thereupon operates and closes its alternate contact, thereby lighting the signal lamp L of operator Y.

Upon receiving" the signal, operator Y plugs plug P into jack J, thereby closing a circuit from ground, battery. relay 2.

sleeve contacts of plug P and jack J, to

ground. The relay 2, upon energization, closes at its left-hand contact a circuit through the filaments of the amplifiers R and R from ground, battery, left-hand contact of relay 2, contact Z1 and filaments in series to ground. At its right-hand armature relay 2 opens the original energizing circuit tor lamp L and transfers the control of this lamp to the back contact of relay 4t.

Operator Y then operates her ringing key K, thereby ringing subscriber B in the usual way and simultaneously cuttingofl current trom the filaments of repeaters R and R by opening contact 76.

Then the ringing key K is released and sul'iscriliier B removes his telephone hook. a circuit is established from ground, through battery, relay 3, lower half of secondary of transformer T, ringcontacts of plug P and jack J, subscribers set, tip contacts of jack J and plug P, through upper half of winding of transformer T to ground. This energizes relay 3. thereby closing its contact which short-ciriifuits the high resistance winding of relay 4. This permits an increased current to flow from battery, through relay 5. and the circuit already traced,.thereby maintaining relay ,4 energized and operating relay 5, which at armature andooritact short-circuits lamp L. it is thus seen that the ins rtion o'li plug i iaclt J lights the lamps L and L; that inseition of plug P in jack J extinguishes lamp L and that removal of receiver from the hook of suhscriber B extinguishes lamp Ii when hey l is not in ringing position.

The connection is now in condition "for amplifying talking current as :tollows: Talking current coming through cord circuit it, plug P, jack J, circulates through the pr1- mar-y of transformer T, where it is transferred to the secondary of transforn'ier T and circulates in the circuit including the network N. From this circuit it is transformed to the secondary of transformer t where it goes to the input side of repeater R and is amplified and goes through the output circuit of repeater B through the circuit including the primary of transformer T. Here it is transformed to the secondary of transformer T, and passes through plug P and ack J to the telephone of subscriber B. In a similar way talking current from subscriber B is amplified as it passes in the opposite direction except that it is sent through the repeater R in a manner similar to the way that talking current in the opposite direction is sent t irough repeater R.

/Vhen subscriber B hangs up his receiver, the relay 3 is deenergized, thus removing the shunt from the high resistance winding oi relay l and thereby increasing the resistance of the circuit which has been traced for relay 5 to such an extent that relay 5 is eeenergized and lamp ll lighted, which now serves as a disconnect signal for operator X. lVithdrawal oi" plug P releases relay l, which closes at its normal contact a circuit for the lamp L, which now serves as a disconnect signal for the operator at Y who removes plug P from jack J, therein, releasing r lay 2. The release of relay 2 breaks the circuit of the filaments oi the amplifiers and all apparatus is restored to normal condition.

The dotted line on, 'm/ serves to distinguish the apparatus individual to the two operators positions, since all the apparatus located on one side belongs to the operators position X and all the apparatus on. the other side of this line is located at the operators position Y.

Parts in Fig. 2, which are similar to those in Fig. 1, are designated by the sa ine reference characters except that the subscript 2 is used. The embodiment shown in Fig. 2 is also provided with signal connections and with means for applying ringing current at either end of the trunkcircuit without sending it through the repeaters. When the operator at X, inserts the plug P, in jack 5,, a circuit is closed from ground, he tery, relay 9, sleeve contacts of plug P and jack J, to ground. This closes the contact of relay 9, but as the contact of relay 10 is open, the

lamp L The energization of relay (5 closes its contact, thereby closing a circuit from ground, front contact of relay 6, right-hand winding of marginal relay 7, lamp 1/ righthand back contact of relay 2,, battery, to ground, thereby lighting lamp 1],. Since relay '5 is a marginal relay, the current through its righthand coil does not close its contacts.

Upon receiving the signal, opera tor at Y, inserts plug P in jack J thereby establishing a circuit from ground through battery, relay 2,, sleeve contacts oi plug P, and jack J,, to ground.

The relay 2,, upon energization, opens the circuit through lamp 1],, and also closes its lctt-hand contact, thereby rendering the re-- peaters ll, and It, operative by means oi current from mound through battery, lefthand contact oi relay 2,, key 79,, filaments oi and ll, in series, to ground.

The application of ringing current to subscriber B, may be done by operating key K, or by operating key K If key K is operated, current is sent through the circuit of in a manner similar to that described above in connection. with Fig. 1. ll key K, is operated, ringing current is sent through phi P, and jack J, to the condenser between the two windings of the prin'iary oi transiornii-us T from whence it goes through the rela. 8, thereby closing its con.- tact and energizing relay 11, which operates lsey K therclry applying ringing current to the circuit of subscriber B in the manner already (lPSCl'lllGCl.

l l hen the subscriber l3, removes his tele phone hook, the relay is energized by our rent from ground through battery, relay 3,, lower hall oi the winding of transformer T plug P, and jack 3' subscribei"s set, to the upper halt oi the winding of trans- :lorn'ier T, to ground. he relay 3,, upon Zation, closes a circuit from ground throi gh contact of relay 3,, left hand winding oi relay 7. battery, to ground. This energizes relay T suiliciently to pull over its armature, thereby breaking the circuit which has already been traced through relay 10 and closing a circuit from ground through battery, left-hand winding of relay 6, forward contact of leithand outer contact of relay through relay 10 opens its contact, thereby extinguishing lamp L It is thus seen that the insertion of plug P, in jackJ lights the lamps L and 1/ that the insertion of plug P, in jack J, extinguishes the lamp L and renders the filaments operative; and that the removal of the hook of subscriber B extinguishes lamp L The amplification of the talking current is not described in connection with Fig.2 since it is identical with that described in connection with Fig. 1.

Replacing the receiver of subscriber B breaks the circuit already traced through relay 3 thereby opening its contact and deenergizing relay 7 and closing its left-hand back contacts, which re-establishes current through relay 10, thereby closing the contact of relay 10 and lighting light L to give the operator X, the disconnect signal it her plug P is still in jack J The withdrawal of plug P from jack J deenergizes relay 6, thereby closing a circuit from ground, lefthand back contact of relay 6, right-hand front contact of relay 2,, lamp L battery, .to ground, thus lighting lamp 'L, to give the operator at Y the disconnect signal. The withdrawal of plug P from jack J, deenergizes relay 2,, thereby opening its lefthand contact to render repeaters R and It, inoperative and all apparatus is restored to normal condition.

What is claimed is:

1.. In a telephone exchange system, a trunk circuit, a subscribers line circuit adapted to be connected to one end of said trunk circuit, an operators link circuit adapted to be connected to the other end of said trunk circuit, an amplifier in said trunk circuit, and means for applying ringing current to said line circuit and simultaneously rendering said amplifier inoperative.

2. In a telephone exchange system, an interoflice trunk circuit, a subscribers line circuit adapted to be connected to one end of said trunk circuit, an operators link circuit adapted to be connected to the other end of said trunk circuit, an amplifier in said trunk circuit, supervisory signals, and means for controlling said supervisory sig nals and rendering said amplifier inoperative.

3. In a telephone exchange system, an incoming trunk circuit, a subscribers line circuit adapted to be connected to one end of said trunk circuit, an operators link circuit adapted to be connected to the other end of said trunk circuit, an amplifier in said trunk circuit, means at the outgoing end of said trunk circuit for rendering said amplitier operative, and means for applying ringing current to sald line clrcuit and simultaneously rendering said amplifier inoperative.

4.. In a telephone exchange system, an interoflice trunk circuit, a subscribers line circuit adapted to be connected to one end of said trunk circuit, an operators link circuit adapted to be connected to the other end of said trunk circuit, an amplifier in said trunk circuit, and means for indicating at one end of said trunk circuit that said trunk circuit has been taken for use and for rendering said amplifier operative.

5. In a telephone exchange system, two operators positions, a trunk circuit therebetween, a link circuit at one of said operators positions adapted to be connected to said trunk circuit for connecting a subscribers line to said trunk circuit, a second subscribers line adapted to be connected to said trunk circuit at the second operators position, an amplifier in said trunk circuit inoperative when said trunk circuit is idle, a signaling device, a solenoid at said second operators position for controlling said device, connections to said solenoid responsive while said amplifier is inoperative to the connection of said link circuit to said trunk circuit whereby the operator at the second position is signalled.

6. In a telephone exchange system, two operators positions, a trunk circuit therebetween, a link circuit at one of saidoperators positions adapted to be connected to said trunk circuit for connecting a subscribers line to said trunk circuit, a second subscribers line adapted to be connected to said trunk circuit at thesecond operators position, an amplifier in said trunk circuit, a signaling device, a solenoid at said second operators position for controlling said device, and means responsive to the connection of said link circuit to said trunk circuit for controlling said solenoid independently of the condition of energization of said amplifier.

7. In a telephone exchange system, two operators positions, a trunk circuit therebetween, a link circuit at one of said operators positions adapted to be connected to said trunk circuit for connecting a subscribers line to said trunk circuit, a second subscribers liine adapted to be connected to said trunk circuit at the second operators position, an amplifier in said trunk circuit, a ringing key at the second operators position, and an additional contact on said ring ing key controlling a condition of said amplifier to render said amplifier inoperative when ringing current is applied to said last mentioned subscribers line.

8. In a telephone exchange system, two operators positions, a trunk circuit therebetween, a link circuit at one of said operators positions adapted to be connected to said trunk circuit for connecting a subscribers line to said trunk circuit, a second subscribers line adapted to be connected. to

said trunk circuit at the second ope 'ators position, a two-Way amplifier in said trunk circuit, and means responsive to the answering of the subscriber for the subscribers line connected at the second operators position to signal the operator at the first position independently oi the condition of energization of said amplifier.

9. In a telephone exchange system, two operators positions, a trunk circuit therebetween, a link circuit at one of said operators positions adapted to be connected to said trunk circuit for connecting a subscribers line to said trunk circuit, a second subscribers line adapted to be connected to said trunk circuit at the second operators position, a two-way amplifier in said trunk circuit, a relay at the second operators position responsive independently of the condition of said amplifier to the answering of the subscriber connected to the trunk circuit at the second operators position, said relay being connected to that side of said amplifier adjacent said second operators position, and contacts controlled by said relay for signaling the operator at the first position.

10. In a telephone exchange system, two operators positions, a trunk circuit therebetween, a link circuit at one of said operators positions adapted to be connected to said trunk circuit for connecting a subscribers line to said trunk circuit, a second subscribers line adapted to be connected to said trunk circuit at the second operators position, a two-way amplifier having input and output terminals permanently connect ed in said trunk circuit, a signalling device at the second operators device controlled by the connection of said link circuit to said trunk circuit independently of the condition of said amplifier, and means responsive to the connection of the subscribers line at the second operators position to the trunk circuit for rendering said amplifier operative and for changing the control connections of said device.

11. In a telephone exchange system, two operators positions, a trunk circuit therebetween, a link circuit at one of said operators positions adapted to be connected to said trunk circuit for connecting a subscribers line to said trunk circuit, a second subscribers line adapted to be connected to said trunk circuit at the second operators position, a two-way amplifier having input and output terminals permanently connected in said trunk circuit, a ringing key in said link circuit for signalling the subscriber for the subscribers line connected to the trunk circuit at the second operators position independently of the condition of energization of said amplifier.

12. In a telephone exchange system, two operators positions, a trunk circuit there between, a link circuit at one of said operators positions adapted to be connected to said trunk circuit for connecting a subscribers line to said trunk circuit, a sec ond subscribers line adapted to be connected to said trunk circuit at the second operators position, a two-way amplifier in said trunk circuit, a source oif signaling current at the second operators position for signaling the subscriber for transmitting signaling current over the subscribers line terminating at said second operators position, and means in said link circuit for con trolling the connection of said source to said line independently of the condition of energization of said amplifier.

13. In a telephone exchange system, two operators positions, a trunk circuit therebetween, a link circuit at one of said operators positions adapted to be connected to said trunk circuit for connecting a subscribers line to said trunk circuit, a second subscribers line adapted to be connected to said trunk circuit at the second operators position, a two-way amplifier in said trunk circuit, a source of signaling current at the second operators position for signaling the subscriber for transi'nitting signaling current over the subscribers line terminating at said second operators position, and means in said link circuit for controlling the connection of said source to said line and for simultaneously rendering said amplifier in operative.

In witness whereof, I hereunto subscribe my name this 19th day of December, A. D.

\VILLIAM H. BENDERNAGEL. 

